The subject matter disclosed herein relates to a switching device configured to switch multiple electrical circuits between two power sources, and more specifically, to a switching device including a double pole, double throw switch operatively connected with a double circuit breaker to selectively connect one of two power sources to electrical loads.
It is known that utility power lines are exposed to harsh environmental conditions and can become inoperable for many reasons, such as inclement weather, ice, falling trees, or animal damage, which may cause a portion of the power grid to fail or blackout. Consequently, many utility power customers install a backup generator to power some or all of the electrical loads present at the residence or business in the event utility power becomes unavailable. The utility power customer may also install a transfer switch which allows one or more loads to be alternately connected with one of the two power sources according to the position of the switch. Referring to FIG. 1, the utility power customer may install a switching device 10 which includes multiple transfer switches 15, where each transfer switch 15 is configured to selectively connect one branch circuit from a load center either to the utility power or to the generator. A circuit breaker 20 is connected between the generator and the load for each of the switched circuits, replacing the circuit breaker in the load center when the load is connected to the generator. The switching device 10 may include a receptacle 25 configured to receive a power cord from the generator. Optionally, the generator may be hard-wired to the switching device 10. The switching device 10 may also include watt meters 30, 35 which provide a visual indication of the amount of power being drawn by the loads.
Historically, it has been known to select a switching device 10 that includes a sufficient number of transfer switches 15 to provide backup power to selected critical circuits within a building, such as a dwelling. A critical circuit may include, for example, a furnace, hot water heater, sump pump, refrigerator, etc. As the number of electronic devices and electric circuits within a dwelling continue to increase, however, the utility power customer may have an increasing number of critical circuits, including, for example, medical equipment, a backup sump pump, and lights in one or more areas of the dwelling. Further, the utility power customer may desire the backup generator to power additional circuits such as an oven, television, or computer. As a result, the number of transfer switches 15 and corresponding circuit breakers 20 required within the switching device 10 continues to increase. The increased number of transfer switches 15 and circuit breakers 20 result in a corresponding increase in the space required to install the switching device 10. Thus, it would be desirable to provide a switching device configured to transfer an increased number of circuits within the same or in a smaller space than a conventional switching device 10.
Additionally, it is common for a utility power customer to add circuits subsequent to initial construction, for example, during a remodel or an expansion of the dwelling. The utility power customer may desire that a portion of the additional circuits be added to the switching device 10 such that they may also be powered by the backup generator in the event of a power failure. However, because the switching device 10 typically provides backup power to a smaller number of circuits via the generator than are powered via the utility grid, all of the transfer switches 15 typically are already connected to circuits. As a result, the utility power customer must either remove an existing circuit or install a larger switching device 10 to add the new circuit. Thus, it would be desirable to provide a switching device 10 that is expandable to allow additional circuits to be easily added for connection to the backup generator.